The present invention relates to the gauges and in particular gauges for measuring the liquid level of liquefied petroleum gases.
As used herein, liquefied petroleum gas (LP gas) refers to either the liquid or vapor state. LP gas is pressurized and stored in a pressure container. The more specific terms of xe2x80x9cliquid LP gasxe2x80x9d will refer to the pressurized gases in the liquid state and the term xe2x80x9cvapor LP gasxe2x80x9d will refer to the vapor phase of such gases. Because the volume of the liquefied gas varies with atmospheric temperature, it is important that the volume of the liquefied gas not be equal to the volume of the storage container otherwise there is a risk of bursting the storage container. Thus a filled container represents a maximum safe volume of liquid LP gas over which is a pressurized vapor LP gas. The liquid level of the liquid LP gas is measured typically by a float gauge. The level of liquid LP gas in the container can also be measured with a fixed liquid level gauge. A fixed liquid level gauge uses a dip tube and a relatively small positive shutoff valve and is designed to indicate when the liquid level in the container being filled reaches a point at which the dip tube communicates with the interior of the container. More typically a fixed maximum liquid level gauge is employed which it is set by proper dip tube length to the liquid level at which a container is filled to its maximum permitted filling limit under applicable safety guidelines. The fixed liquid level gauge allows pressurized vapor LP gas to be expelled through the gauge while the liquid level is below the dip tube as the tank is being filled. When the liquid level reaches the lower end of the dip tube, liquid begins to be expelled from the gauge, and the condensation of water vapor in the air can be seen enunciating that liquid has risen to the height indicated by the fixed liquid gauge.
Float gauges typically are constructed such that a float is positioned inside the container which rests on the liquid surface and the position of the float is transmitted through a lever mechanism and linkages to a pointer and dial outside the container. The motion of the float is conveyed to the gauge typically by magnetic linkage through a non-magnetic plate so that no LP gas is released to the atmosphere. The filling operation and the limit of fill is controlled by the weight of liquid LP gas or some prefer to utilize the fixed maximum liquid level gauge in order to ensure that the maximum safe permissible volume is not exceeded when the container is filled. Employment of both a float actuated contents gauge or the fixed liquid level gauge in the past required two openings in the container. There has been a need to minimize the number of openings required in a container and to simplify design and manufacturing costs, the present invention has the advantages requiring only one opening in the container for both gauges, simplifies construction and reduces the number of parts required while still providing both a float contents gauge and a fixed maximum liquid level gauge.
One object of the invention is to provide a gauge head configured to serve both as a head for a float gauge and for a fixed liquid level gauge. In one aspect, the invention is a body having a top and bottom with a passageway passing through the body having a first end and a second end and the body defines a receptacle to receive the end of a float support member. In the preferred embodiment the first end of said passageway is adapted to receive a dip tube for the maximum liquid level gauge and a valve is positioned at the second end of said passageway. In a preferred embodiment the body also includes a recess on the top surface to receive a dial assembly adapted to magnetically link with the magnet on a float arm assembly. In the preferred embodiment, the gauge is designed to be mounted on the top of the pressure vessel.
Another object of the invention is to provide for a simplified construction in which a separate dip tube for the maximum liquid level gauge is not required. In this embodiment, the invention has a gauge head for a float and fixed liquid level gauge comprising of body having a top and bottom, the body defines a receptacle for receiving a float support member of a float arm assembly and also defines a passageway having a first and second end, said first end communicating with the receptacle for the tubular member of the float arm assembly. The second end of the passageway is adapted to receive a valve.
In another aspect, the present invention is a combined float and fixed maximum liquid level gauge head comprising a body having a top and bottom and defining a receptacle for the float support and defining a passageway having a first and second end said first end communicating with the receptacle for the float support member and said second end adapted to receive a valve. The float support member defines a passageway and when attached to the receptacle extends from the bottom of the head, said support member""s passageway communicates with the passageway in said head to form an extended passageway by joining the passageways. In another embodiment the support member is the length of a maximum filled dip tube. In another embodiment the support member is supplied with an orifice at a distance from the head where a maximum filled dip tube would be.
In another aspect, the present invention relates to a complete gauge having both a fixed liquid level and float gauge. The gauge is formed from one of the heads described above with the attachment of a dip tube and float gauge components having a top and bottom with a bushing at the top and a bushing at the bottom to hold rotatably a shaft having a magnet there. The shaft has a top and bottom. The top being equipped with a magnet and the bottom with a gear to engage a gear assembly attached to the float arm.
Movement of the float causes the float arm to move, rotating the shaft and the attached magnet. The magnet on the shaft is magnetically linked with a magnet in the dial assembly. Rotation of the magnet on the shaft rotates the magnets in the dial assembly causing the pointer to move.